1. Field of the Invention
The present invention relates generally to electric lamps and more particularly to electric lamps that use fossil or hydrocarbon fuels to heat volatile substances so they may be dispensed.
2. Description of the Related Art
Many people utilize portable devices to heat volatile substances such as mosquito repellents as part of camping gear or for various outdoor activities where there exists a threat of mosquitoes. Such volatile substances most commonly are either insect control active ingredients or air treatment materials, such as air fresheners. The mosquito repellent systems are manyfold, and for camping or special uses, it is desirous that the mosquito repellent system be portable.
An example of a prior art mosquito repellent system is that of U.S. Pat. No. 5,928,605, assigned to the instant assignee. In that device, a butane cartridge supplies fuel to uniformly heat a thermally conductive plate upon which a mat containing volatile insect repellent is positioned. When the plate is sufficiently heated, the insect repellent is volatilized and thereby dispensed. The evaporation of the insecticide and its dispersion causes mosquitoes to be repelled for a reasonable space around the portable mosquito repellent device.
Another prior art product is that identified as OFF sold by SC Johnson (U.S. Pat. No. 6,663,838 and others). In that device, a candle is provided that heats a mat placed in a vertical position atop thereto. The heat from the lighted candle causes insecticide in the mat to evaporate therefrom and be dispersed.
Both prior art devices lack versatility and have limitations. In particular, the prior Thermacell product does not have a light available to illuminate an area, whereas the OFF product has a flame which acts both as a source of light to illuminate an area and as a source of heat to volatilize a substance to be dispensed. The small flame required to volatilize the volatile substance is not very luminous and its intensity cannot be controlled. Moreover, a user cannot turn off the light source without terminating the dispersal of insect repellent.
U.S. Pat. No. 6,033,212, assigned to the instant assignee, discloses a lamp which both provides light and also dispenses a volatile substance. The light is produced by burning a hydrocarbon fuel, with the excess heat being harnessed to heat a thermally conductive plate upon which a mat containing the repellant is placed However, this device similarly suffers from a poor quality light and does allow a user to turn off the light source without terminating the dispersal of insect repellent.